diff --git a/library/aes.c b/library/aes.c
index 5cd96ec..23efdb8 100644
--- a/library/aes.c
+++ b/library/aes.c
@@ -1713,8 +1713,10 @@
 #if defined(MBEDTLS_CIPHER_MODE_CTR) || defined(MBEDTLS_CIPHER_MODE_CFB)
     size_t offset;
 #endif
-#if defined(MBEDTLS_CIPHER_MODE_CTR)
+#if defined(MBEDTLS_CIPHER_MODE_CTR) || defined(MBEDTLS_CIPHER_MODE_XTS)
     int len;
+#endif
+#if defined(MBEDTLS_CIPHER_MODE_CTR)
     unsigned char nonce_counter[16];
     unsigned char stream_block[16];
 #endif